With the continuously shrinking of the process node of the semiconductor process technology, the conventional metal-oxide-semiconductor (CMOS) devices which use silicon dioxide as a gate dielectric layer and polycrystalline silicon (poly silicon) as a gate electrode layer have faced problems such as the increase of leakage currents and the depletion of gate electrode layers. In order to solve these problems, materials with a high dielectric constant (high-K) are used to substitute silicon dioxide as the gate dielectric layer, and metals are used to substitute the poly silicon as the gate electrode layer (so called a high K metal gate, HKMG).
The problems faced by CMOS such as high leakage current, etc, have been solved by the HKMG process. However, when semiconductor devices made by the HKMG process is integrated with the process for making an entire chip, some problems arise. For example, it is difficult to integrate the HKMG process of core devices with the fabrication process of peripheral in/out devices (I/O devices). Therefore, a fabrication process that can integrate the HKMG process of core devices with the process of I/O device is needed in semiconductor manufacturing industry. The disclosed methods and systems are directed to solve one or more problems set forth above and other problems.